In part 1 of my How to Practise series, I’m going to give you a framework for practising focusing.
Ryu wrote about having a “keeper rate” of 2-6% when he shoots an event. 20 odd images from 600-900. When I started shooting sports I had a keeper rate of about 100%. I never discarded any images and thought they were all perfect. I saw beauty in every image. As time went by, I started looking over my old images and found that I didn’t like a lot of them. Then I started looking at them more critically and I noticed that the ones I didn’t like were the ones that were not in focus. Something I hadn’t really noticed when I first looked at the photo.
Having come from shooting film in the era of manual focus lenses and film where it’s impossible to check a photo’s focus until the film’s been processed and a photograph printed, I never placed much emphasis on whether a photo was in focus. When you print something out as a 4 x 6, images that are not in focus doesn’t look too bad. However, with digital, and Auto Focus technology, you can look at your images instantly and zoom to 100% instantly, or after you’ve downloaded your images to your computer. This gives you a way to practise focusing that wasn’t available in the film era.
I’m also surprised that in the hundreds of photography books and articles I’ve read I’ve never come across anything that taught a photographer how to use a DSLR’s auto focus function and how to practise using it to get sharp pictures.
So, here’s version 1.0 of my exercise on how to practise using your Auto Focus in your camera to get achieve images that are properly focused and sharp:
- Set your camera’s focus mode to AF-S (Single-servo AF) on Nikon and on Canon
- Set your camera on single point AF, use the centre point for this exercise
- Separate the AF activation so that auto focus is initiated with the dedicated AF-ON button and not with the shutter button (this is the preferred setting for most sports photographers). This is custom setting a5 on a Nikon D3 and on a Canon
- Using your sports lens, eg a 70-200mm, rack it out to 200mm
- If your lens has vibration reduction, turn it off
- Using aperture priority or manual exposure mode, set the aperture to the widest for the lens eg f 2.8 and a shutter speed of no faster than the inverse of the focal lens eg 1/200th of a second for a 200mm lens. You’ll have to adjust the ISO to achieve proper exposure. I suggest you do this indoors as outdoors on a bright day you’ll struggle to have the ISO low enough
- Now pick a subject, a person looking at you is good, or it can be a book shelf with lots of books, or anything you can focus on. Don’t worry about the composition, just focus on something in the scene. If you selected a person, a good place is to focus on the eye ball or the eye lashes. If a bookshelf, some lettering on the spine of a book. Whatever it is, try to make sure it’s the centre of your image and fills at least 50% of the frame
- Focus by tapping on the AF-ON button, don’t hold it down, take a breath, hold it, and then squeeze the shutter
- Repeat 10 times: Take 10 shots of the subject, each time removing the camera from your eye, and then putting it back again. I don’t want you to just hold the camera to your eye and press the shutter 10 times.
- Now check the focus. Are all your 10 shots exactly the same? In focus, no motion blur?
- Now, change the exposure by increasing the ISO and reducing the shutter speed by 1/2 stop. So if you were shooting at 1/200th of a second, try 1/160th of a second. You’ll need to increase your ISO to compensate
- Repeat the exercise, shoot 10 images. All sharp? Keep slowing down the shutter speed in increments until you’ve got no less than 50% of sharp images. Now you now what your limits are with the lens
- If your lens has vibration reduction, you can turn it on now and see if you can improve the number of sharp images. You might be surprised by the result
Here’s a set of photos I took of my computer monitor at various shutter speeds. As you can see, hand holding a 70-200mm lens at 1/25th is perfectly doable, without vibration reduction.
And here is a typical image I would discard for being out of focus after reviewing it at 100%/200% crop.
This is a great exercise because you’ll get to know your lens and how far you can push hand holding your camera before you’ll need a tripod or other support. You’ll also know how slow your shutter can get before you need to use artificial lighting. With practise, you can keep getting your shutter speed slower and slower which is critical if you want to do artistic techniques like panning and zoom blur.
In Part 2 I’m going to talk about how to practise keeping focus on a moving subject.
Have fun shooting!
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